Cascade – Motion & Transitions for UI Toolkit

Runtime motion engine for UI Toolkit (UXML/USS) — Unity 6000.0+, pure C#, zero dependencies

Springs: presets + stiffness/damping/mass, velocity-preserving interrupts, perceptual duration dial

Verbs: Fade, MoveX/Y/To, ScaleTo, Rotate, SlideIn, BackgroundColor, TextColor, Width, Height, Size, Top, Left, Value, Nudge

Sequencing: parallel groups, .Then() chains, delays, loops, Pause/Resume/Cancel, OnSettled, async/await

Stagger, variants (named states), enter/exit + screen transitions, hover/press/focus interactions

No-code UIAnimator: selector rules, preset browser, create-in-place, edit-mode live preview

AI/JSON: SequencePreset.FromJson/PlayJson, JSON schema, Motion.Describe() manifest, AI-GUIDE + prompt pack

Samples: full demo gallery (copyable code per section) + 10 Starter Presets

Docs in Documentation~ (getting started, recipes, API reference, AI-GUIDE)

Supported OS: every Unity-supported platform (no native code)

UI Toolkit gave you components. It never gave you motion.

Cascade adds springs, variants, stagger, screen transitions and hover/press micro-interactions — written in C#, built in the inspector with live preview, or generated by an AI assistant.

PLAY IT FIRST - https://twitchedd.itch.io/cascade-blocks

Every pixel of motion in that game is Cascade.

WHY PAY WHEN FREE TWEEN LIBRARIES EXIST?

Free tween libraries animate values from code, and they're great at it. Cascade is a UI Toolkit motion SYSTEM: your non-programmer teammates build entrances, hover states and screen transitions from the inspector with live preview; you get UITK-native lifecycle safety (panel detach, display toggling, USS quirks handled), springs with velocity handoff, variants, and a preset library — out of the box.

WHAT'S INSIDE

- Springs that survive interruption — velocity relay, no dead-stops

- AI-ready: describe motion to your assistant, paste back validated JSON, it plays; errors coach the AI to fix itself (ships with AI-GUIDE.md + JSON schema + prompt pack)

- Variants: To("open") / To("closed") named states

- Stagger any list of elements in one line

- Enter/exit + screen transitions with display-safe Show/Hide

- Hover / press / focus micro-interactions, interruption-safe

- No-code UIAnimator: selector rules, preset browser, create-in-place, edit-mode live preview

- 10 Starter Presets + full demo gallery with copyable code per section

- Reduced-motion accessibility (full / reduced / crossfade / none)

- Zero per-frame GC (test-enforced), zero dependencies, async/await throughout

- Unity 6000.0+, every Unity-supported platform, no native code

TIERS

Cascade Lite (free, MIT) covers the core tween engine with the full verb set and async/await. Cascade Pro adds everything above. Both install as clean UPM packages.